A Clemson student is no longer facing a DUI charge in connection to a crash that killed a 68-year-old man, according to a prosecutor. Robert Barrett, 68, of Clemson, was hit and killed on March 15 on Highway 93 at Perimeter Road, Chief Deputy Coroner Andrew Wilson said. Michael Lee Lyon III was charged with DUI after the crash. Kurt Tavernier, Clemson University Municipal Court prosecutor, said the charge against Lyon was deemed "nolle prossed" on Monday, which means the prosecution will not go forward. Tavernier says after an extensive investigation by the Clemson University Police Department, which included reviewing video, witnesses and measurements from South Carolina Highway Patrol, he concluded that there was a lack of evidence to support a conviction. Below is background on what police say happened at the scene the night of the crash: Police say they spoke with Lyon at the scene and noticed he had a strong marijuana odor coming from him and appeared to be in shock with glossy and dilated eyes.Officers say that they also smelled a strong odor of marijuana coming from the vehicle he was driving. Witnesses told Clemson PD that they saw Barrett get hit by a truck and that Barrett was not using the crosswalk during the time of the incident. During the investigation, Lyon was told to take a field sobriety test but refused, police say. After officers made further observations, Lyon was arrested and taken to the Clemson University Police Department's Datamaster Room for a Breathalyzer test, which Lyon refused to give.Lyon was also taken to Oconee Memorial Hospital where he also refused to give a urine test, police say.